An enum in C++ consists of a set of named integer constants. It allows for creating a new data type where each value is represented by a unique name rather than a numeric value, enhancing the readability of the code. This means that an enum can only hold one of the values that you've defined.

When dynamic memory allocation is done using new, it's necessary to release that memory using delete to prevent memory leaks in C++. This ensures that every byte of memory allocated is properly released, maintaining the health and efficiency of the system.

When using switch-case statements, it's essential to remember to include the "break" statement at the end of each case. Without it, the program may execute subsequent cases, leading to unintended behavior known as "fall-through." The "break" statement ensures that once a match is found, no other cases are executed.

In C++, the modulo operator % is used to determine the remainder of a division operation between two numbers. For example, 7 % 3 would yield a result of 1, as when 7 is divided by 3, the remainder is 1. It's a very useful operator, especially in situations that require calculations around loops and array indices.

Function call overhead is the extra time and resources needed when a function is called. Using inline functions can help reduce this overhead, especially in recursive algorithms, because the function's code gets inserted (or "inlined") at each point where the function is called, eliminating the need for the typical call and return process, which can be resource-intensive.

The switch-case structure in C++ is best suited for scenarios where a single variable's value needs to be checked against a series of constants, often seen with enumerated values. It's a cleaner and more readable alternative to a long series of if-else statements in such cases.

The "do-while" loop in C++ always executes its body once before checking the condition. So even if the condition in the "while" part is "false", the body of the loop will execute once. This differentiates it from the "while" loop which checks the condition before the first execution.

The "default" case in a switch-case statement is executed when none of the provided "case" conditions match the switch expression's value. It serves as a fallback and handles unspecified or unexpected values, ensuring that the switch has a response for all potential input. It is similar to the "else" in if-else.

In C++, a function pointer points to the address of a function. The correct syntax for declaring a function pointer is type (*pointer_name) (parameter list). In the given options, int (*func)() is the correct way to declare a function pointer returning an int.

In C++, a function declared with a void return type does not return any value. It is used when the function needs to perform an action but doesn't need to send any data back to the calling function.

Smart pointers in C++ are template classes that manage the lifetime of dynamically allocated objects. They ensure that the objects they manage are properly deleted, thus preventing accidental deletions or memory leaks. Overloading the delete operator or enabling strict type-checking wouldn't inherently prevent accidental deletions.

weak_ptr is a smart pointer that holds a non-owning reference to an object managed by shared_ptr. It doesn't affect the reference count and won't prevent the object from being deleted.